It is impossible to commercially produce a high-strength metallurgical coke by charging low-fluidity blended raw material coal fines having a maximum fluidty of up to 20 d.d.p.m. in the form of fine particles as they are into a conventional coke oven battery. Production of only a low-strength coke is inevitable in this manner. There is therefore proposed a method for producing a formed coke, as a solution to the above-mentioned inconvenience, which comprises charging and carbonizing green briquettes obtained by compression-forming the blended raw material coal fines of a low fluidity mentioned above in a conventional coke oven battery.
According to this method, the strength of individual pieces of formed coke is certainly improved. However, the low fluidity of the blended raw material coal fines prevents mutual agglomeration between pieces of formed coke, and in consequences, it is impossible, in a conventional coke oven battery, to discharge therefrom a formed coke with the use of a coke pusher.
A conventional coke oven battery for producing metallurgical coke comprises coking ovens for carbonizing a coal charge, combustion chambers for causing combustion of a fuel gas, regenerators for storing the remaining heat of a combustion waste gas and sole flues for guiding the combustion waste gas into a stack. The coking ovens and the combustion chambers are alternately arranged on the regenerators and thus form a coke oven battery. Each combustion chamber comprises many flues where a fuel gas is burnt. Coke is produced by heating and carbonizing a coal charge in the coke ovens on both sides of the combustion chamber through oven walls by said combustion. The produced coke is pushed horizontally over a distance of about 16 meters by a coke pusher installed on one side of the coking ovens, and thus discharged therefrom from the other side of the coking ovens. Pieces of the formed coke produced from green briquettes obtained by compression-forming the blended raw material coal fines of a low fluidity as mentioned above are not in mutual agglomeration, and there is no gap between the oven wall and the formed coke. The force applied by the coke pusher therefore also acts laterally, i.e., in the direction of the oven wall, thus causing a considerably high frictional resistance between the formed coke and the oven wall. The resulting abnormally raised load current of the coke pusher not only makes it very difficult or even impossible to discharge the formed coke to the outside of the oven, but also may cause a serious trouble such as breakage of the oven wall.
In order to produce a formed coke from blended raw material coal fines of a low fluidity as mentioned above, therefore, it is necessary to use a coke oven battery provided with a special oven sole permitting discharge of produced formed coke by a coke pusher, or a shaft furnace permitting discharge of produced formed coke by gravity. However, it is impossible, in such an oven and furnace, to produce a formed coke efficiently in a large quantity.